Improve functional testing by adding condition validation support function

[schrolla]

💡 Summary

Functional testing often requires changing tenant configuration settings in order to validate certain use cases. Some changes, however, may be executed asynchronously or the new value is reflected with delay causing a test to intermittently fail depending on the load on the API service at any given time.

The idea is to add a support helper method that would just loop given a command/expression until the expression returned true or timed out given a timeout period. That way, you could set a pre-condition and have it wait until that condition became true or a pre-defined time period elapsed.

Motivation and context

Having an easy to reference and use pre-defined function to validate that a config item shows as changed or matches a given state prior to running a test will be convenient for developers to build robust tests that return predictable results.

Implementation notes

Please provide details for implementation, such as:

• Create a new PowerShell function that accepts an expression or function to execute and a timeout value
• Make sure that the timeout parameter defaults to a reasonable time frame to prevent test run delays
• Timeout period should also be bounded to prevent delays in execution, if timeout period is exceeded, fail the continue test but issue warning
• Convert several candidate functional tests (existing or new) to use the new function
• Run existing functional tests to validate they work as intended, including running as part of existing testing workflows

Acceptance criteria

How do we know when this work is done?

• Successfully defined new support function that delays test until an expression or function returns true or timeout expires
• Tests to run new functional tests using support function run successfully
• New function is documented via PowerShell docstring to help developers understand usage
• Functional testing README updated with details and examples of how to use the support function when building tests

[schrolla]

This is a duplicate of #1364. Closing as duplicate.